1.Remove the (red?) environmental seal retaining ring @ the very bottom of the first stage (not the one above it) with a pin spanner.
2.Let the round plastic (transmitter) thing fall out. Now you have a non-sealed functioning regulator.
3.Put the 1st stage (WITH the second stage, HP gauge, and LP inflator hose attached ) on a full-ish tank.
4.Plug the IP gauge into the inflator hose.
5.Pressurize the regulator.
6.With a 6mm(?) hex-head wrench placed in hex-shaped hole on the bottom of the regulator you can turn slightly R or L to alter the IP.
7.Purge the second stage as necessary.